In a transmission electron microscope, an electron beam is directed to a sample, and electrons having traversed the sample are detected in an analyzing system located downstream of the sample in the beam path of the transmission electron microscope. Information relating to properties of the sample are derived from the detected electrons. The electrons incident on the sample interact with the sample. Such interaction includes, for example, scattering of the electrons, deflection by a certain angle and change of a kinetic energy of the scattered electrons.
One possible type of analysis of the electrons having traversed the sample includes separating electrons having traversed the sample substantially unscattered from electrons having experienced a deflection by a significant angle due to their interaction with the sample. The scattered and the un-scattered electrons can be separately detected, and, for example, an image which is generally referred to as a bright field image, can be generated from those electrons having traversed the sample substantially unscattered. Moreover, an image generally referred to as a dark field image can be generated from the electrons scattered by a significant angle.
A further type of analysis of electrons having traversed the sample includes analyzing a kinetic energy of the electrons. The electrons incident on the sample may excite processes within the sample resulting in an energy loss of the electrons. For example, information relating to a chemical composition of the sample can be obtained from an analysis of such energy loss. The analysis of the kinetic energy of the electrons may involve an energy filter having an entrance image plane and an entrance pupil plane.
Some further type of analysis of electrons having traversed the sample may include subjecting different portions of the beam of electrons having traversed the sample to different phase shifts, and to subsequently superimpose the beam portions with each other and to detect a resulting interference pattern. Such type of analysis is commonly known as phase contrast microscopy.
A still further type of analysis of the electrons having traversed the sample may involve separating the beam into two beam portions using a bi-prism, superimposing the separated beam portions with each other and generating an interference pattern. Phase information relating to the sample can be obtained by analyzing the interference pattern. Such type of analysis is commonly referred to as electron beam holography.
The different types of analysis of electrons having traversed the sample require different configurations of an analyzing system. It is generally difficult to perform plural different types of analysis using a same or similar configuration of the transmission electron microscope.